Dental Tribune Asia Pacific No. 9, 2016

14 Dental Tribune Asia Paciﬁc Edition | 9/2016 TRENDS & APPLICATIONS Fillings were placed on the teeth,someofwhichwereseverely damaged, with help of an adhesive composite system (Syntac and Tetric EvoCeram, both Ivoclar Vivadent) prior to planning of the permanent restoration. This way, we were able to better assess the severity of the destruction and obtain a better idea of where the potential preparation margins would be located. In order to achieve an aesthetic and func- tional rehabilitation, we had to create an adequate tooth mor- phology on the basis of a suitable width–length relationship of the teeth, establish an anterior ca- nine-protected dynamic occlu- sion and rebuild the VDO. The destructive processes to which the damaged teeth had been exposed had to be stopped and a stable occlusion had to be created. The patient wanted a long-lasting rehabilitation based on a minimally invasive pro- cedure and tooth-coloured re- storations. The ﬁnal restoration would include adhesively bonded glass-ceramic veneers and onlays. Glass-ceramic crowns would be used for those teeth that were severely damaged (teeth #13–23). In view of the fact that these extensive aesthetic and func- tional modiﬁcations had to be combined with a re-adjustment of the VDO, the clinical team decided on the following treat- ment plan: 1. Fabrication of a study wax-up to assist in the creation of an ade- quate aesthetic and functional tooth morphology 2. Intra-oral evaluation of the wax-up (mock-up) by the patient with the help of a diagnostic matrix 3. Transfer of the increase in the VDO as determined with the wax-up to a stabilisation splint for functional evaluation 4. Tooth preparation guided by the diagnostic matrices and re- ciprocal determination of the maxillomandibular relation- ship with a split stabilisation splint 5. Trial of the direct temporaries on the basis of the outer con- tours established in the wax-up 6. Impression taking and prompt fabrication of the permanent glass-ceramic restorations in the laboratory 7. Try-in and permanent adhesive placement of the glass-ceramic restorations. Clinical implementation and long-term evaluation Crowns made of lithium di- silicate ceramic in the layering technique (IPS e.max Press and IPS e.max Ceram, both Ivoclar Vivadent) were used for the maxil- laryanteriorregion,whichshowed a high degree of tooth destruction (large composite ﬁllings; Fig. 3a). In the mandibular anterior region, glass-ceramic veneers layered on refractory dies (IPS d.SIGN, Ivoclar Vivadent) were placed (Fig. 3b). Full-contour onlays pressed from leucite-reinforced glass-ceramic and customised using the stain- ing technique were placed in the posterior region (IPS Empress Esthetic, Ivoclar Vivadent). The onlays exhibited a minimum oc- clusal thickness of 1.5 mm (Fig. 4). Cementation was achieved with a multicomponent adhesive system in conjunction with the to- tal-etch technique (Syntac) and a dual-curing, low-viscosity luting composite, using rubber dam iso- lation where possible (Fig. 5). At a follow-up examination conducted more than 11 years after the restorations had been placed, it was found that the 15 posterior onlays showed no damage (Figs. 6a & b). However, we had noticed a cracking on the glass-ceramic onlay of tooth #24 after more than six years of clinical performance. For this reason, the onlay had sub- sequently been replaced. Close in- spection of the mandibular ante- rior veneers revealed a severe wear facet on veneer #43 (Figs. 7a–c). Similar to the other veneers, this area was in direct contact with the lithium disilicate crowns on the maxillary anterior antagonists during dynamic occlusion. Conclusion Given the enamel-like proper- ties of the glass-ceramic material, the minimally invasive methods used for this case provided a long-lasting approach to restoring the function, aesthetics and bio- mechanics of the dentition while minimising the damage to the biological structures (Figs. 8a–f). Beneﬁcial clinical long-term re- sults have been described and conﬁrmed in several studies. Parafunctions, endodontically treated teeth and an adequate amount of enamel, among other factors, have been ﬂagged as risk factors inﬂuencing the success of these restorations. Against such a background, the additive wax-up techniqueusedinthiscaseproved to be beneﬁcial. Combined with a diagnostic matrix, this technique allows for a conservative approach to tooth preparation and helps to preserve the remaining enamel during preparation. In addition, an in vitro investigation has shown en- couraging data regarding the stress distribution in ceramic onlay restorations. It is, however, important to note that prepa- rations should have soft and rounded transitions to prevent stress peaks from occurring. Inrecentyears,wehavemainly used glass-ceramic onlays based on lithium disilicate in conjunc- tion with the staining technique. Given its increased strength, this material allows the minimum thickness to be reduced by one- third to just over 1 mm, further increasing the amount of tooth structure that can be preserved during preparation. Owing to their extremely high strength and optimal marginal integrity, glass-ceramic onlays appear to be ideally suited for restoring the function, aesthetics and biomechanical properties of abraded and eroded posterior teeth. They offer an opportunity to circumvent traditional pros- thetic measures that are more invasive and involve higher bio- logical costs. Oliver Brix is a dental techni- cian and the head of in- novative den- taldesign in Bad Homburg in Germany. He can be contacted at Oliver-Brix@ t-online.de. Prof. Daniel Edelhoff is a Senior Dental Surgeon and Chair of the Policlinic for Dental Pros- thetics at the Ludwig Maximilians University in Munich in Germany. He can be contacted at daniel.edelhoff@med. uni-muenchen.de. 8a 8b 8c 8d 8e 8f Figs. 8a–f: Portrait photographs taken more than 11 years after placement of the restorations. The aesthetic and functional requirements of the patient were and continue to be to her full satisfaction. “...the minimally invasive methods used for this case provided a long-lasting approach to restoring the function, aesthetics and biomechanics of the dentition while minimising the damage to the biological structures...”

Dental Tribune Asia Pacific No. 9, 2016

Pages Overview